Switched DC-DC converters comprise a switchable power stage, wherein an output voltage is generated according to a switching signal and an input voltage. The switching signal is generated in a digital control circuit that adjusts the output voltage to a reference voltage. The switched power stage comprises a dual switch consisting of a high-side field effect transistor (FET) and a low-side FET, an inductance and a capacitor. During a charge phase, the high-side FET is turned on by the switching signal to charge the capacitor. During a discharge phase the high-side FET is turned off to drain the capacitor. The switching signal is generated as a digital pulse width modulation signal with a duty cycle determined by a control law. The control law may be implemented by a PID compensator generating a PWM signal.
PWM is recommended for applications that require a fixed frequency or in case certain frequencies need to be avoided. This can be the case in a system like data acquisition, mobile phones, etc. However, when a load current exhibits a regular pattern, PWM based control may lead to avoidable switching losses. Hence, what is needed is a solution that saves energy.